US 6,660,560 B2Granted

No-flow underfill material and underfill method for flip chip devices

AssigneeDelphi Technologies, Inc.

InventorsArun K. Chaudhuri, Derek B. Workman, Matthew R. Walsh

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Abstract

A no-flow underfill material and process for underfilling a flip chip component. The underfill material comprises at least three polymer layers. A first of the layers overlies terminals of a substrate to which the component is to be mounted. The first and second layers are substantially free of fillers, while the third layer contains a filler material to reduce its CTE. The underfill process entails placing the component so that solder terminals thereof penetrate the first, second and third layers and contact the terminals on the substrate. Because only the third layer contains filler material, penetration of the underfill material by the solder terminals is substantially unimpeded. The solder terminals are then reflowed, during which the filler material migrates into the unfilled first layer and the first, second and third layers consolidate and cure to form a single underfill layer.

Claims11

Dependent claims

A method of underfilling a flip chip component with a no-flow underfill material, the method comprising the steps of:

forming the no-flow underfill material to comprise a first layer of an uncured first polymer dielectric material on a terminal of a circuit substrate, a second layer of an uncured second polymer dielectric material on the first layer, and a third layer comprising an uncured third polymer dielectric material on the second layer, the first and second layers being substantially free of a particulate filler, the third layer containing a particulate filler material having a CTE lower than the CTE of the third polymer dielectric material;
penetrating the first, second and third layers with a solder terminal of the flip chip component so that the solder terminal contacts the terminal;
heating the first, second and third layers and the solder terminal so that the solder terminal melts, the particulate filler material in the third layer migrates into the first layer, and the first, second and third layers consolidate and cure to form a single underfill layer, and then
cooling the molten solder terminal and the underfill layer so that the molten solder terminal forms a solid electrical interconnect that is metallurgically bonded to the terminal and the underfill layer encapsulates the interconnect and contacts both the flip chip component and the circuit substrate.

1 more element

A method of underfilling a flip chip with a no-flow underfill material, the method comprising the steps of:

depositing a first layer of an uncured first adhesive material on a terminal of a circuit substrate, the first layer containing a flux compound but being substantially free of a particulate filler having a CTE lower than the CTE of the first adhesive material;
depositing a second layer of an uncured second adhesive material on the first layer, the second adhesive material having a higher viscosity than the first adhesive material, the second layer being substantially free of a particulate filler having a CTE lower than the CTE of the second adhesive material;
depositing a third layer of an uncured third adhesive material on the second layer, the third adhesive material having a higher viscosity than the second adhesive material, the third layer containing a particulate filler material having a GTE lower than the CTE's of the first, second and third adhesive materials;
penetrating the first, second and third layers with a solder bump of the flip chip so that the solder bump contacts the terminal;
heating the first, second and third layers and the solder bump so that the solder bump melts, the particulate filler material in the third layer migrates into the first layer, and the first, second and third layers consolidate and cure to form a single underfill layer, and then
cooling the molten solder bump and the underfill layer so that the molten solder bump forms a solid electrical interconnect that is metallurgically bonded to the terminal and the underfill layer encapsulates the interconnect and contacts both the flip chip and the circuit substrate.

3 more elements

Dependencies are inferred from the claim text.

Facts

Application: 09/949,556Filed 10 Sep 2001
Published: US 2003/0049411 A113 Mar 2003
Granted: 9 Dec 2003
Term ends: Not estimatedThe source records don’t support an estimate.

Classification18 codes

H10W 74/012
Manufacture or treatment: of encapsulations on active surfaces of flip-chip devices, e.g. forming underfills
B32B 3/10
Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products…:…
H10W 74/15
Characterised by their shape or disposition: on active surfaces of flip-chip devices, e.g. underfills
H10W 72/073
Connecting or disconnecting: of die-attach connectors